Steep sided islands

I am using SbuilderX 3.15 with Prepar3d 4.5 although I am sure this issue applies to older versions and other tools. It appears flatten polygons (which includes water terrain) flatten an area outside the area of the polygon. This makes having small steep sided islands impossible, the water flatten flattens the island. Is there some form of workaround that anyone has come up with? The best think I came up with is creating water terrain with no flatten and the judiciously using bare flattens a distance from the shore, but this has its limitations since the bare flattens appear to do a rectangle which still somewhat affects the island if I have 0 sea level water right up to the shore.

Some excellent tutorials to review (if you have not already done so) are:

Terrain Design

File Description:
Terrain Design for Flight Simulator X

This simple illustrated document explains the basic concepts in Flight Simulator X terrain, and how to change them using SBuilder for FS X. Make new water bodies, roads, vehicle traffic, airport flattens, remove autogen, add more detail - anybody can do it easily and quickly.
My most sincere apologies - I am unable, for lack of free time, to offer support of any kind. For questions or problems, please post in the Avsim scenery design forum.

File Description:
It is very easy to create your very own high-resolution, custom (photo-real) ground textures. This document explains the concepts and techniques and illustrates the use of SBuilderX with which you can quickly and easily download aerial images and make this type of scenery. So, why hesitate? Make Flight Simulator scenery as real as it gets! Very sorry - no support of any kind is offered. Please do not write. For any questions, please post in the Avsim Scenery Design Forum.

File Description:
The Autogen Annotator is a powerful tool for modifying the autogen of default ground textures or adding autogen to custom (photo-real) ground. This document illustrates the use of the tool, and includes a pictorial guide to all autogen object types. Very sorry - no support of any kind is offered. Please do not write. For any questions, please post in the Avsim Scenery Design Forum.